Air circuit breakers as described within U.S. Pat. No. 3,095,489 entitled "Manual Charging Means for Stored Energy Closing Mechanisms of Electric Circuit Breakers" and U.S. Pat. No. 3,084,238 entitled "Ratchet Mechanism for Charging a Closing Spring in an Electric Circuit Breaker" include operating mechanisms that are mainly exposed to the environment. Since the air circuit breakers are rated to carry several thousand amperes of current continuously, the exposure to convection cooling air assists in keeping the operating components within reasonable temperature limits.
Various accessory devices are used with such air circuit breakers to provide auxiliary function along with overcurrent protection. One such accessory is the bell alarm accessory that provides local and remote indication as to the occurrence of circuit interruption. U.S. Pat. No. 5,502,286 entitled "Bell Alarm and Lock-Out for High Ampere-Rated Circuit Breakers" describes a bell alarm accessory used with so-called "insulated case" circuit breakers wherein the circuit breaker interrupting components are completely enclosed within an insulating plastic enclosure. This patent describes one such bell alarm accessory that interacts with the circuit breaker operating mechanism to activate the bell alarm upon circuit interruption and to prevent the closing of the circuit breaker contacts until the accessory is manually reset.
U.S. patent application Ser. No. 08/875,595 filed on Jun. 19, 1997 entitled "Circuit Breaker Bell Alarm Accessory with Lockout" provides a bell alarm accessory that provides local as well as remote indication of such circuit interruption as well as preventing circuit breaker contact closure until and unless the accessory has become manually reset. The bell alarm accessory described therein is similar to that disclosed within U.S. Pat. No. 5,502,286 entitled "Bell Alarm Accessory Module".
In most circuit breakers employing a bell alarm for status indication of the circuit breaker contacts, it is a requirement that the circuit breaker operating mechanism be reset before the bell alarm can be manually reset to indicate the circuit breaker closed condition. It would be more convenient, in certain applications, to allow the bell alarm accessory to become automatically reset immediately upon closure of the circuit breaker contacts without the requirement of manual intervention.
One example of a bell alarm automatic reset function in high-ampere rated air type circuit breakers is found within U.S. patent application Ser. No. 08/904,324 filed Jul. 31, 1997 entitled "Circuit Breaker Bell Alarm Accessory with Automatic Reset".
Such high-ampere rated air type circuit breakers operate in the range of 2500 to 5000 amperes such that the large circuit breaker operating components are arranged with the bell alarm reset components in a particular manner. When low-ampere rated air type circuit breakers that operate in the range of 150 to 1500 amperes require bell alarms with automatic reset function, the arrangement of the circuit breaker operating smaller components do not readily allow the use of the high-ampere rated bell alarm reset accessory.
One purpose of the invention is to describe a bell alarm accessory for use with smallampere rated air type circuit breakers that is automatically reset upon response of the smallampere rated circuit breaker operating mechanism to close the circuit breaker contacts.